Why bigger tires?

B

bobg333

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Oct 5, 2007
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As some of you know, I recently acquired a new (to me) truck. It needs new tires. The factory spec tires are 245 75 16s. The truck currently has 265 75 16s. Now I know that bigger tires look lots cooler and give me more ground clearance (in this case, about 5/8"!!). But are there any real advantages? And what are the drawbacks? Obviously the flywheel effect and the additional weight of a bigger tire must have a negative effect on stopping distance and brake wear. Anything else?

If you have bigger tires, why did you buy them?

If you bought bigger tires, did you make any mods to the brakes to compensate?

[I do plan on doing some semi serious (Puertocitos to Gonzaga Bay) fourwheeling if that is a consideration.]

Bob in LA
2000 Ram 2500 CTD 4X4 QC w/ 04 Grandby
 
there is a great write up that scott brady did over on expeditionportal.com about this issue...i stuck with the 265/75/r16 on my tacoma and have been happy with them overall. i thought a lot about the 255/85 but decided against them for a number of reasons...mainly performance (loss of power with stock gearing and reduced mpg's) as well as the fact that with my current suspension set up i would have had to do some fender trimming...also, things like price, selection, and availability played a role as well...i'll try to locate that write up and link it for you...
 
tire size/tire pressure

Bob thought i'd throw my thoughts on tire size.I agree that for most fwc/atc users stock size tires get the job done 99% of time.Only if you are into real hard core 4 wheeling (which unless you have a highly modified 4x4) would i consider anything larger than 1 size bigger.That being said i feel that more important than tire size is tire pressure.Your remark of a trip to Gonzaga bay is a good example.We have made this trip at least 20 times with out a flat or blow out,and i feel the only reason is that i ALWAYS air down my tire pressure when i leave the pavement and always air up when on pavement or high speed gravel roads.Of course you must slow down if you air down,so if you are going to play racer the above advice is not worth using! And yes it is a pain to air down/air up,but much easier than changing a tire! When i get out on the back roads and trails i do not see any of the super raised road trucks that drive in town/freeways on a daily basis,but i do see plenty of stock 4x4's 2x4's and every other type of daily drivers!I would like to hear other opinions on tire size etc.

Drive slow and enjoy "Its the journey"
Les lqhikers
 
Mileage may vary, depending on how your truck is geared now it could increase, decrease or remain the same. Generally one or two sizes over stock don't require much if any in the way of modifications. When it comes time to get new tires for my truck I plan on about two sizes over stock.

I agree about airing down offroad. I take my jeep down to eight psi in the rough stuff. I haven't yet aired down the dodge partly due to not having an air compressor for it (i have one in the jeep), partly haven't done the kind of terrrain that calls for it, and partly because I'm unsure just what I can do safely. The cummins is heavy and I'm a lot more conservative with the truck than I am the Jeep.
 
My thoughts on bigger tires is find a size that you can get in about any tire shop or gas station. I used to run 255/85 16's on my 01' F350 but after ruining a tire in Utah and not being able to find one, I decided to go back to the stock size of 265/75 16. They had plenty of those available. It doesn't look as good with the smaller tires, but knowing if I need a tire in the middle of nowhere my chances are better.
 
Tires

Hi Bob,

Yes there are many pros and cons for changing tire sizes.

If you think about it 5/8” is not that much for ground clearance. Remember that they use those sizing charts measurements with no load and is for total height and not for the half that is sitting near the road surface squatting with a load on it. Rim width comes into play hear also. Compare same rim size for height of tire. You won’t gain much ground clearance and would be better by driving with a precise tire placement to maintain good ground clearance.

For your driving and where you are going you might think about the stock size but go with a beefier sidewall plies to help when you air down to protect the sidewall. Also it will help when you are really putting a side force on the sidewall at a side slope with the extra weight.

What everybody else has said is very good advice and can echo them below.

Stock vehicle with bigger tires cons. It all depends as to how much bigger you are going from stock size to make the effect worse:
Loss of torque to rear wheels and that equals less gas mileage.
Longer stopping distance because bigger diameter and more un-sprung weight.
Brakes may wear out sooner.
Speedometer will be off.
May be harder to find a off-the-shelf replacement at stores.
Harder for wife to get in and out.
Wider tires throw more rocks and mud up the side of you vehicle.
Going really big could mean sheet metal work and ring and pinion ratio change (and the list could go on).

There are a lot of Pros for bigger tires from stock if your vehicle is set up for more extreme stuff but it sounds like yours is not so I won’t go there.
 
Thanks

Thanks for all the input. I'm always impressed with high level of thoughtful response in this group. Happy Trails, Bob
 
If its a new vehicle, recalibrating the speedo can probably done with a simple update to the computer.

Not just tire size, but rim size is important too. My old Chevy had 16.5 wheels. I had a flat near truckee and had to go all the way to reno to find a tire to fit. Those were so out of date I wound up having to buy new wheels so I could get tires.
 
I went 2 sizes bigger.

Lots of good information so far. For what it's worth...

My truck came with 245/75R16 tires and the truck was pretty low. I found I was bottoming the front end on even mild trails that my other trucks wouldn't have had an issue with. I went to 285/70R17 tires primarily for the additional ground clearance. They also have a larger contact patch so I get better traction, but reduced fuel mileage. Like your truck, mine has plenty of horse power and torque, so the taller final gear ratio isn't a factor unless I tow a really heavy trailer, in which case I can put the stock wheels and tires back on. I did have to trim 1/2 inch of a plastic valance on the front bumper and pull back the front fender liners a little to get them to fit without any rubbing. I purchased a computer for about $250 that allows me to adjust the speedometer and odometer for the larger size tires. Otherwise, they would have been off by 10%.

As for rims, most tire manufacturers list suggested rim sizes for their tires and at least one shop in town would not put larger tires on the small rims (6.5" wide) that came with my truck, because I already had the largest tires size suggested for the rim and they didn't want to accept the liability in case of a tire failure. Finally, when looking for new rims you want to get one that has "J" or "JJ" at the end of the rim size (i.e. 17 X 8.5 J) because they have a deeper bead which holds the tire better. I think most new rims have the J designation.
 
Bob-
This thread is a little old now, so maybe you've already made up your mind about tire size but I can share my experience.

I have a 2006 Cummins 6-speed 4x4. I swapped out the stock E rated Michelins (approx 31.5" tire) that came with my truck for a set of 35" D rated BFG All-Terrains. I never tow anything with my truck and don't really plan to, so I wasn't concerned with losing any towing capacity. I have the 3.73 rear end, not the 4.10 so I was a little concerned at the time about losing power, but the Cummins didn't notice the difference at all. My mileage in town went down about 1 mpg and I gained a solid 2 mpg on the highway.

The BFG's are every bit as quiet as the stock Michelins and actually ride much better; the on-road traction is stunning for an off-road tire. Off the pavement the difference is night and day. In my opinion, it's the best money I've spend on the truck so far.

As far as the Dodge vs. Jeep comparison, the Cummins is tractor off-road - just point it in the direction you want to go, and you'll slowly roll over anything you come across. Once you get used to it you'll find it to be a very capable off-road rig.

-Kris
 
I hope my truck never gets in this position. Speaking of tires reminded me I have this shot of my Jeep.
 

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Update

I ended up sticking with the 265/75's and I did get the BFG A/Ts. Very happy with them so far.
 
Hmmmm.... bobg333 and craig333

Are you guys brothers that had different mothers and fathers? :D:D:D

Mike

P.S. I am just trying to be funny... I am not trying to upset anyone.
 
Wait'll he sees Guido's Kenworth with the blacked out FWC on the back coming around the corner!
 
Wait'll he sees Guido's Kenworth with the blacked out FWC on the back coming around the corner!
Like this...

Mike
 

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